Video signal transmission method, superimposed information transmission method, video signal output device, video signal reception device, and video signal recording medium

ABSTRACT

A spread code string containing a plurality of chips per interval in one horizontal interval or containing a plurality of chips per interval in one vertical interval is generated synchronously with the vertical sync signal at the generation star timing having a period of one vertical period or having a period of a plurality of vertical periods. The generated spread code string repeats over a plurality of horizontal intervals or a plurality of vertical intervals so that the chips having the same data are arranged in spatial direction of the vertical direction or the time axis direction in picture unit. The additional information is spectrally spread so that the chips having the same data are arranged at least in the interval in each 1 horizontal interval or in each 1 vertical interval of the above-mentioned repetition interval, and the generated spectral spread signal is superimposed on the video signal. Thereby, the additional information spectrally spread and superimposed on a video signal is prevented from being removed and being deteriorated, and the quantity of additional information to be superimposed on the video signal is increased.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of application Ser. No.09/007,702, filed on Jan. 15, 1998, now U.S. Pat. No. 6,253,020, thedisclosure of which is hereby incorporated by reference herein, andclaims priority from Japanese Application No. 09/009439, filed on Jan.22, 1997.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method, device, and video signal recordingmedium which is capable of performing a method that outputs a videosignal having an additional information superimposed thereon, receivesand extracts the received additional information, and performsduplication prevention control using the extracted additionalinformation, for example, as in the case that a video signal recorded ina recording medium is played back, the video signal is transmittedtogether with an information for preventing duplication, the transmittedvideo signal is received, and recording on another! recording medium isrestricted or inhibited.

2. Description of Related Art

VTR (Video Tape recording devices) has been popularized in daily life,and many kinds of software which can be played back on a VTR aresupplied abundantly. Digital VTR or DVD (Digital Video Disks) playbackdevices have been available commercially now, and provide images andsound of exceptionally high quality.

On the other hand, there is, however, a problem in that softwareapplications of this great abundance can be copied without restriction,and several methods have already been proposed to inhibit duplication.

For example, though the method is a method which inhibits duplication ofan analog video signal not directly, one method to prevent copying usesa difference in the AGC (Automatic Gain Control) system, or in the APC(Automatic Phase Control) system, for example, between the VTR recordingdevice and a monitor receiver for displaying the image.

For example, the method which utilizes the difference in AGC system, inwhich a VTR performs AGC using a pseudo sync signal inserted in thevideo signal and a monitor receiver employs a different AGC system notusing the pseudo sync signal, is an example of the former, in detail,when an analog video signal is recorded in an original recording medium,a very high level pseudo sync signal is previously inserted as a syncsignal for AGC, and the very high level pseudo sync signal is insertedin the video signal to be supplied from a playback VTR to a recordingVTR as a sync signal for AGC.

Alternately, the method which utilizes the difference of APCcharacteristics between a VTR and receiver as in the case that APC in aVTR can follows the color burst signal in a video signal with a shorttime constant but APC in a receiver follows with a relatively long timeconstant is an example of the latter, in detail, the phase of the colorburst signal of a video signal is previously inverted partially when theanalog video signal is recorded in an original recording medium, and thecolor burst signal having partially inverted phase is outputted as avideo signal to be supplied from a playback VTR to a recording VTR.

As the result, the monitor receiver which receives the analog videosignal from the playback VTR plays back the image correctly withoutbeing affected by the pseudo sync signal in AGC or without desiredaffection of the partial phase inversion of the color burst signal usedfor APC.

On the other hand, in a VTR, which is supplied with the analog videosignal from the playback VTR into which pseudo sync signals have beeninserted or which has been subjected to color burst signal phaseinversion control as described herein above, for receiving such analogvideo signal and for recording the analog video signal in a recordingmedium, proper gain control or phase control based on the input signalcannot be performed, and so the video signal is not correctly recorded.Even if this signal is played back, therefore, normal picture and soundcannot be obtained.

As described herein above, in the case that involves an analog videosignal, the prevention is not a method for directly inhibitingduplication but is a method for viewing an abnormally played backpicture which can not viewed normally. Such prevention method is apassive duplication prevention control.

On the other hand, in the case that a digitized information, forexample, video signal is involved, an anti-duplication signal or ananti-duplication control signal comprising, for example, a duplicationranking control code, is added as digital data to the video signal andrecorded on the recording medium, so as to prevent or controlduplication of the image.

FIG. 1 is a basic structural diagram of a duplication apparatus forduplicating digitized information, a digital information played back bythe digital playback device 110 is sent to a digital recording device120 through a digital transmission line 101, and the digital recordingdevice 101 duplicates the digital information if duplication ispermitted and does not duplicate the digital information if duplicationis not permitted.

An anti-duplication control information in the form of additionalinformation is recorded in a recording medium 111 placed on the digitalplayback device 110 in addition to a digital main information. Theanti-duplication control information indicates control content such asduplication inhibition, duplication permission, or generationrestriction. The digital playback section 113 reads out the informationfrom the recording medium 111, acquires the anti-duplication controlinformation together with the digital main information, and sends themto the digital recording medium 120 through the digital transmissionline 101.

An anti-duplication control signal detection section 122 of the digitalrecording device 120 detects the anti-duplication control signal out ofthe information received from the digital transmission line 101, andjudges the control content. The judgement result is sent to a digitalrecording section 121.

If the judgement result of the anti-duplication control signal from theanti-duplication control signal detection section 122 indicatespermission of recording of the digital information inputted through thedigital transmission line 101, then the digital recording section 121converts the input digital signal to a digital information suitable forrecording, and writes it in the recording medium 123, that is, recordingis performed. On the other hand, if the judgement result of theanti-duplication control signal from the anti-duplication control signaldetection section 122 indicates duplication inhibition, then the digitalrecording section 121 does not perform recording processing of the inputdigital information.

Further, if the judgement result of the anti-duplication control signalfrom the anti-duplication control signal detection section 122 indicatespermission of recording of only the first generation, then the digitalrecording section 121 converts the input digital signal to a digitalinformation suitable for recording, and writes it in the recordingmedium 123, that is, recording is performed, and additionally, convertsthe anti-duplication control signal in the form of additionalinformation to a signal for indicating duplication inhibition(duplication inhibition of next generation), and records it in therecording medium 123. Therefore, the video signal can not be duplicatedfurther using the recording medium 123 in which the information isrecorded.

As described herein above, in the case of digital connection that themain information signal and anti-duplication control signal added as anadditional information are supplied to a recording device in the form ofdigital signal, because the anti-duplication control signal is containedin the digital data to be transmitted, duplication prevention controlsuch as duplication inhibition is performed consistently in a recordingdevice using the anti-duplication control signal.

In the case that the digital playback device in FIG. 1 is, for example,a digital VTR, in order to monitor the played back video signal andaudio signal, only both the video signal, that is the main informationsignal, and audio signal are converted to an analog signal through a D/Aconversion circuit 113 and guided to an analog output terminal 114connected usually to a monitor receiver.

As described herein above, though the playback device is a device forplaying back digital signals, the anti-duplication control signal is notcontained in the analog signal guided to the analog output terminal 114.Therefore, in the case of analog connection that an analog device suchas analog VTR is connected to the analog output terminal 114,duplication of the information signal is undesirably possible.

Though it is considered that the anti-duplication control signal issuperimposed and added on the D/A converted video signal and audiosignal, it is difficult that the anti-duplication control signal isadded, extracted in a recording device, and used in duplicationprevention control without deterioration of the D/A converted videosignal and audio signal.

Therefore, heretofore in the case of analog connection, only the passiveduplication prevention method utilizing the difference in AGC system orthe difference in APC characteristics between a VTR and monitor receiverdescribed herein above has been an available duplication preventioncontrol method.

However, in the case of the duplication prevention control methodutilizing the difference in AGC system or APC characteristics between aVTR and monitor receiver described herein above, it can happen to recordthe video signal normally and to fail in even the passive duplicationprevention dependently on the AGC system or APC characteristics of therecording device side. Further, it can happen to cause disturbance ofplayed back picture on the monitor receiver. These are problems induplication prevention control.

The inventors of the present invention has proposed previously a methodin which a anti-duplication control signal is spectrally spread, thespectrally spread anti-duplication control signal is superimposed on theanalog video signal, and the video signal is recorded in the form ofdigital record or analog record (refer to U.S. patent application Ser.No. 08/75510) as a duplication prevention control method which can solvethe problem described herein above and is effective for both analogconnection and digital connection without deterioration of the playedback picture and sound.

According to this method, a PN (Pseudorandom Noise) sequence code(referred to hereinafter as PN code) used as a spread code is generatedat a sufficiently fast rate and spectrally spread by multiplying it bythe anti-duplication control signal. In this way, a narrow-bandhigh-level anti-duplication control signal is converted to a wide-bandlow-level signal which does not affect adversely the video signal orsound signal. This spectrally spread anti-duplication control signal isthen superimposed on the analog video signal, and recorded in arecording medium. In this case, the signal to be recorded in a recordingmedium may be an analog signal or a digital signal.

In this method, because the anti-duplication control signal isspectrally spread and superimposed on the video signal as a wide-bandlow-level signal, it is therefore difficult for a person who wishes toillegally duplicate the video signal to remove the anti-duplicationcontrol signal which is superimposed on it.

However, it is possible to detect and use the superimposedanti-duplication control signal by performing inversion spectral spread.This anti-duplication control signal is therefore supplied to therecording device together with the video signal. In the recording side,the anti-duplication control signal is detected, and duplication isconsistently controlled according to the detected anti-duplicationcontrol signal.

However, in the case of system in which an anti-duplication controlsignal is spectrally spread and it is superimposed on the video signal,in some cases, the spectrally spread anti-duplication control signal isremoved, deteriorated or changed by using the noise removal system forvideo signals.

For example, in the case of the noise removal system for removing noisein a video signal by utilizing correlation between picture elements ofvideo signals, between frame intervals, or between fields, thedifference is taken between adjacent video signals of adjacenthorizontal scanning lines, adjacent fields or adjacent frames, and thedifference obtained is removed as noise.

In this case, it can happen that the anti-duplication control signalspectrally spread and superimposed on the video signal is calculated asthe difference, and it is removed as mentioned above. And when it isremoved, it can happen that the spectrally spread anti-duplicationsignal is changed to a different spectrally spread anti-duplicationcontrol signal.

Further, when the noise removal system mentioned above is used, thoughnot the all anti-duplication control signals spectrally spread andsuperimposed on the video signal, it can happen that an anti-duplicationcontrol signal superimposed on the video signal is removed partially,and an anti-duplication control signal deteriorates. In this case, acorrect anti-duplication control signal superimposed on the video signalcannot be extracted, and the playback prevention control correspondingto an anti-duplication control signal is not performed.

Further, for example, in the case that a so-called horizontally-longwide television image of 16:9 aspect ratio is converted into atelevision image of standard 4:3 aspect ratio, or in the case that atelevision image is converted conversely, when picture element data arethinned out or interpolated in the horizontal direction, or a picture isenlarged or reduced in right and left direction, the anti-duplicationcontrol signal spectrally spread and superimposed on the thinned outvideo signal disappears, or the spectrally spread anti-duplicationcontrol signal using the interpolated data becomes discontinuous, andthen it can happen that an anti-duplication control signal is impossibleto be restored to the original state by spectrum reverse diffusion.

Further in the case that NTSC system is converted into PAL system, or inthe case of inverse conversion, when, system conversion betweendifferent television systems having different number of scanning linesis performed, the same problem as described above can happen in thiscase during performing thinning out and interpolation processing inhorizontal line unit.

Because the video signal of 1 field is composed again using the videosignal of several fields when special speed playback such as slowplayback or double speed playback is performed on a VTR, in this videosignal composed again, it can happen that the spectrally spreadanti-duplication control signal becomes discontinuous, and ananti-duplication control signal cannot be restored to the original stateby inversion spectral spread.

In the case that so-called cut editing is performed and video signal infield unit is thinned out, in video signal after cut editing, thespectrally spread anti-duplication control signal becomes discontinuoussimilarly, and the anti-duplication control signal becomes impossible tobe restored to the original state by way of inversion spectral spread.

The conventional spectral spread can involve only small quantity ofinformation to be superimposed on as the additional information such asanti-duplication control signal, it is also a problem.

In view of the above-mentioned problems, it is the object of the presentinvention to provide a method, device, and video signal recording mediumwhich involves performance that the above problems are eliminated, andadditional information spectrally spread superimposed on the videosignal is transmitted consistently to the receiver, the completeadditional information can be extracted, and the quantity of additionalinformation to be superimposed is increased.

SUMMARY OF THE INVENTION

The first video signal transmission method in accordance with thepresent invention is a transmission method for transmitting a spectrallyspread additional information superimposed on a video signal comprises;

a spread code generation step for generating a spread code stringcontaining a plurality of chips per interval in 1 horizontal interval ora plurality of chips per interval in 1 vertical interval at thegeneration start timing having the period of 1 vertical period or havingthe period of a plurality of vertical periods synchronously with thevertical sync signal, a spread code repetition step for repeating thespread code strings generated in the spread code generation step over aplurality of horizontal intervals or a plurality of vertical intervalsso that chips having the same data are arranged in the verticaldirection or the spatial direction of the time axis direction in pictureunit,

a spectral spread step for spectrally spreading an additionalinformation so that the same data is contained at least in an intervalin the each 1 horzontal interval or an interval in the each 1 verticalinterval in the repetition interval using the spread code stringsgenerated in the spread code repetition step, and

a superimposition step for superimposing the spectral spread codegenerated in the spectral spread step on the video signal.

The second video signal transmission method in accordance with thepresent invention is a video signal transmission method for transmittinga video signal on which a spectrally spread additional information issuperimposed, which method comprises;

a spread code generation step for generating a plurality of spread codestrings which contains 1 chip or a plurality of chips per interval in 1horizontal interval or 1 chip or a plurality of chips per interval in 1vertical interval and in which chips having the same data are arrangedin the vertical direction or the spatial direction of the time axisdirection in picture unit in the continuous plurality of horizontalintervals or a plurality of vertical intervals at the generation starttiming of the period of 1 horizontal period, 1 vertical period, or aplurality of vertical periods synchronously with the video sync signalby means of a plurality of spread code generation means,

a spread code switching step for switching the plurality of spread codestrings in the horizontal direction, vertical direction, or the spatialdirection,

a spectral spread step for spectrally spreading the additionalinformation data having the same content for at least the same series ofspread code string using the spread code string switched in the spreadcode switching step, and

a superimposition step for superimposing the spectral spread signalgenerated in the spectral spread step on the video signal.

According to the first video signal transmission method in accordancewith the present invention, chips are arranged in the vertical directionin a plurality of horizontal intervals repeated in the spread coderepetition step.

Therefore, even if noise removal utilizing correlation of the videosignal in horizontal line unit in the plurality of horizontal intervals,the spectral spread signal superimposed on the video signal is notdetected as the difference, and hence the spectral spread signal willnot be removed or deteriorated.

Similarly, even if thinning out or interpolation in horizontal line unitis carried out due to picture size conversion involving aspect ratiochange or change of the number of scanning lines for changing televisionsystem, the superimposed additional information remains reproducible,and is transmitted consistently.

Chips having the same data of the spectral spread signal are arranged inthe spatial direction of the time axis direction in picture unit(referred to simply as time axis direction) in a plurality of verticalintervals repeated in the spread code repetition step. Therefore, whennoise removal system utilizing correlation between fields or frames ofthe video signal is used, the spectral spread signal superimposed on thevideo signal is not detected as the difference even though thedifference is taken between fields or frames, hence the spectral spreadsignal will not be removed and deteriorated. Even if special speedplayback or cut edition is performed, similarly, the spectral spreadsignal is transmitted consistently.

Because spectral spread is performed using the different spread coderespectively for a plurality of horizontal intervals or a plurality ofvertical intervals in the first video signal transmission method, it ispossible to superimpose different additional information using thedifferent spread codes, and thus it is possible to increase the quantityof superimposed additional information.

As described herein above, the spectrally spread additional informationwill not be removed or deteriorated even if noise removal systemutilizing correlation of the video signal is used, and even if thinningout or interpolation in horizontal line unit in the vertical directionof the video signal is carried out, the additional informationsuperimposed on the video signal is extracted consistently.

According to the second video signal transmission method in accordancewith the present invention, the additional information is spectrallyspread with switching the spread code of different series supplied fromthe different spread code generation means every plurality of horizontalintervals or plurality of vertical intervals, and is superimposed on thevideo signal. Hence, chips generated using the different spread code isprovided also in the horizontal direction, and the chips can be arrangedin the time axis direction. As the result, the same effect as thatobtained in the invention described in claim 1 is obtained, and furtherit is possible to increase the quantity of additional information to besuperimposed on the video signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram for illustrating the conventional structure ofa duplication prevention control system.

FIG. 2 is a block diagram for illustrating one embodiment of the videosignal output device in accordance with the present invention.

FIG. 3 is a block diagram for illustrating one example of the PNgeneration control section of the video signal output device inaccordance with the present invention.

FIG. 4 is a diagram for describing one example of the PN code generationtiming signal generated in the video signal output device shown in FIG.2.

FIG. 5 is a block diagram for illustrating an exemplary structure of thePN generation section of the video signal output device shown in FIG. 2.

FIG. 6 is a block diagram for illustrating an exemplary structure of thePN repetition section of the video signal output device shown in FIG. 2.

FIG. 7 is a conceptual diagram for describing generation of the PN code(mapping) used in the video signal output device shown in FIG. 2.

FIG. 8 is a diagram for showing the relation between the SSanti-duplication control signal and video signal in the form ofspectrum.

FIG. 9 is a block diagram for illustrating one embodiment of the videosignal recording device to which a video signal reception device inaccordance with the present invention is applied.

FIG. 10 is a conceptual diagram for describing generation of the PN code(mapping) generated using the video signal output device shown in FIG.2.

FIG. 11 is a conceptual diagram for describing generation of the PN code(mapping) generated using the video signal output device shown in FIG.2.

FIG. 12 is a conceptual diagram for describing generation of the PN code(mapping) used in the video signal output device shown in FIG. 2.

FIG. 13 is a block diagram for illustrating another example of the PNgeneration control of the video signal output device shown in FIG. 2.

FIG. 14 is a block diagram for illustrating another embodiment of thevideo signal output device in accordance with the present invention.

FIG. 15 is a diagram for describing one example of the PN codegeneration timing signal generated in the video signal output deviceshown in FIG. 14.

FIG. 16 is a diagram for describing another example of the PN codegeneration timing signal generated in the video signal output deviceshown in FIG. 14.

FIG. 17 is a block diagram for illustrating another embodiment of thevideo signal recording device to which the video signal reception devicein accordance with the present invention is applied.

FIG. 18 is a conceptual diagram for describing generation of the PN code(mapping) used in the video signal output device shown in FIG. 14.

FIG. 19 is a block diagram for illustrating one example of the PNgeneration control in the video signal output device shown in FIG. 14.

FIG. 20 is a conceptual diagram for describing generation of the PN code(mapping) used in the video signal output device shown in FIG. 2.

FIG. 21 is a diagram for describing the dividing into blocks in picturecompression system.

FIG. 22 is a block diagram for illustrating one example of a circuit inthe case that the SS anti-duplication control signal is superimposed onthe compressed video signal data using the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of a video signal transmission method, superimposedinformation extraction method, video signal output device, video signalreceiving device, video signal recording medium in accordance with thepresent invention will be described in detail with reference to thedrawings hereinafter.

A video signal output device applied to a recording/playback device ofDVD (a digital video disk) (ref erred to as DVD device herein after) isdescribed herein after. The description about sound signal system isomitted to simplify explanation.

[Video Signal Output Device of the First Embodiment]

FIG. 2 is a block diagram for illustrating an information signal outputdevice 10 (referred to simply as output device hereinafter) of the firstembodiment. In other words, the output device 10 is corresponding to aplayback system of a DVD device in the first embodiment.

In FIG. 2, in a recording medium 100, digitized images and audio signalsare recorded together with an anti-duplication control signal asadditional information. The recording medium 100 is a DVD in thisembodiment. The anti-duplication control signal may be recorded on theinnermost or outermost TOC (table of contents) or a track area known asthe directory, or it may be inserted on a track in which image data oraudio data is recorded, namely, on the same track but on the areadifferent from the data recording area. An example described hereinafteris of the latter case, namely the case that the anti-duplication controlsignal is read out at the same time as the video signal is read out.

The anti-duplication control signal may have the content of generationrestriction for permitting only the first generation, or may be a signalfor inhibition or permission of video signal duplication, and composedof 1 bit or several bits only for description.

As shown in FIG. 2, the output device 10 of the embodiment is providedwith a read out section 11, decoding section 12, anti-duplicationcontrol signal extraction section 13, SS (SS stands for spectral spreadhereinafter) anti-duplication control signal generation section 14, syncseparation section 15, PN generation control section 16, PN generationsection 17, PN repetition section 18, addition section 19, D/Aconversion circuits 191 and 192.

The read out section 11 extracts a playback video signal component S2from the signal S1 obtained by playing back the recording medium 100,and supplies it to the decoding section 12 and anti-duplication controlsignal extraction section 13.

The decoding section 12 performs decoding processing on the playbackvideo signal component S2, generates a digital video signal, andsupplies it to the D/A conversion circuit 191. The D/A conversioncircuit 191 D/A converts the digital video signal to generate an analogvideo signal S3 having the sync signal, and supplies it to the syncseparation section 15 and addition section 19.

The anti-duplication control signal extraction section 13 extracts theanti-duplication control signal S4 added to the playback video signalcomponent S2, and supplies it to the SS anti-duplication control signalgeneration section 14.

On the other hand, the sync separation section 15 extracts thehorizontal sync signal H and vertical sync signal V from the analogvideo signal S3, and supplies it to the PN generation control section16.

The PN generation control generates an enable signal EN for indicatingthe interval where a PN code is generated, PN code reset timing signalRE (abbreviated as reset signal RE hereinafter) for indicatinggeneration start timing of a PN code, and clock signal CLK using thehorizontal sync signal H and vertical sync signal V as the referencesignal.

FIG. 3 is a block diagram for illustrating the PN code generationcontrol section 16 of this embodiment. As shown in FIG. 3, the PNgeneration control section 16 of this embodiment is provided with a PNgeneration timing signal generation section 161, PN clock generationsection 162 having PLL, and timing signal generation section 163, andthe horizontal sync signal H and vertical sync signal V from the syncseparation section 15 are supplied to the PN generation timing signalgeneration section 161 and timing signal generation section 163, and thehorizontal sync signal H is supplied to the PN clock generation section162 from the sync separation section 15.

The PN generation timing signal generation section 161 generates a resetsignal RE having the vertical period for determining repetition periodof the PN spread code string used for spectral spread as shown in FIG.4(A) using the vertical sync signal V as the reference signal.

The PN generation timing signal generation section 161 generates a PNgeneration enable signal EN using the horizontal sync signal H (refer toFIG. 4(B)) as the reference signal in this example. In this example, thePN generation enable signal EN is generated as a signal for generating aPN code from the PN generation section 17 during 1 vertical interval N(N is an integer of 1 or larger) vertical interval apart. In FIG. 4(C)the PN generation enable signal EN is generated during 1 horizontalinterval with 1 vertical interval apart. As shown in FIG. 4(C), theenable signal EN is low active.

The PN clock generation section 162 generates a PN clock PNCLKsynchronous with the horizontal sync signal H using the PLL. The PNclock PNCLK is a clock for determining the chip period of the spreadcode.

The timing signal generation section 163 generates various timing signalused in the output device 10 based on the horizontal sync signal V andvertical sync signal H.

The PN generation enable signal EN, PNcode rest signal RE, and PN clocksignal PNCLK generated in the PN generation control section 16 aresupplied to the PN generation section 17. The PN generation enablesignal EN and PN clock signal PNCLK are also supplied to the PNrepetition section 18.

The PN generation section 17 generates a PN code correspondingly to theclock signal PNCLK, enable signal EN, and PN code reset timing signalRE. In detail, the PN generation section 17 is reset in response to thereset signal RE at the vertical period in this example, and generates aPN code string PS having a pre-determined code pattern from its head.Further, the PN code generation section 17 generates a PN code string PSin response to the clock signal PNCLK only while the PN generationsection 17 is activated by the enable signal EN and in the conditionready for PN code generation (enable condition).

In this example, as described herein above, because the PN generationsection 17 is in the condition ready for PN code generation while theenable signal EN is in low level, the PN generation section 17 is readyfor PN code generation every second horizontal interval as shown in FIG.4 (C), and generates a PN code at the rate of 1 chip every 1 clock ofthe clock signal PNCLK. In this case, because the PN generation section17 is not reset in 1 vertical interval, different PN code strings PN11,PN12, PN13 . . . are generated respectively on the above mentioned everysecond horizontal interval as shown in FIG. 4(D). However, because thePN generation section 17 is reset at the head of the vertical intervalin response to the reset signal RE, in each vertical interval, differentPN code strings PN11, PN12, PN13, . . . are generated respectively onevery horizontal interval similarly.

FIG. 5 is a block diagram for illustrating the structure of the PNgeneration section 17. The PN generation section 17 of this examplecomprises 15 D-flip-flops REG1 to REG 15 which constitutes a 15 stepshift register and exclusive OR circuits EX-OR1 to EX-OR3 for operatinga suitable tap output of the shift register. As described herein above,the PN generation section 17 generates M series of PN code strings PSbased on the enable signal EN, PN clock signal PNCLK, and PN code resttiming signal RE. The PN code string PS generated by the PN generationsection 17 is supplied to the multiplication circuit 163.

In the case of this example, the clock frequency of the clock PNCLKsupplied to the PN code generation section 17 is, for example, 500 kHz,generates the total 4095 chips of the PN code string in 1 verticalinterval by generating the PN code string on all the every secondhorizontal interval in 1 vertical interval.

The PN code strings PS supplied from the PN generation section 17obtained as described herein above is supplied to the PN repetitionsection 18, and the enable signal and clock PNCLK form the PN generationcontrol section 16 is also supplied to the PN repetition section 18.

FIG. 6 is an exemplary structure of the PN repetition section 18. Indetail, the PN code repetition section 18 is composed of a switchcircuit 181 and a shift register 182 having steps for every chips of thePN code contained in 1 horizontal interval. The above-mentioned PN codestring PS is supplied to the one input terminal a-side of the switchcircuit 181 and an output of the sift register 182 is supplied to theother input terminal b-side.

The enable signal EN is supplied as a switching signal of the switchcircuit 181, the switch circuit 181 is switched to the input terminala-side in the interval where the PN code string is generated due to thelow level enable signal EN, on the other hand, switched to the inputterminal b-side in the interval where the PN code string is notgenerated due to the high level enable signal EN. The clock PNCLK issupplied to the shift register 182 as a shift clock.

Accordingly, the PN code string PS comprising PN code strings PN11,PN12, PN13, generated during the every second interval in the PNgeneration section 17 is transferred respectively to the sift register182 through the switch circuit 181. Though no PN code string is suppliedfrom the PN generation section 17 in the residual horizontal intervals,because the switch circuit 181 is switched to the input terminal b-side,the sift register 182 outputs repeatedly the PN code strings PN11, PN12,PN13, . . . of 1 horizontal interval extracted during the priorhorizontal vertical respectively.

As described herein above, in the case of this example, the PN codestring generated every second interval in the PN generation section 17is repeated on the subsequent horizontal interval respectively, andconsequently the PN repetition section 18 generates the PN code stringPSr in which the respective PN code strings PN11, PN12, PN13 . . . ineach 1 horizontal interval continues over two horizontal intervals asshown in FIG. 4(E). The PN code string PSr supplied from the PNrepetition section 18 is then supplied to the SS anti-duplicationcontrol signal generation section 14.

The SS anti-duplication control signal generation 14 spectrally spreadsthe anti-duplication control signal S4 extracted by the above-mentionedanti-duplication control signal extraction section 13 using the PN codestring PSr, and generates a spectrally spread anti-duplication controlsignal (referred to as SS anti-duplication control signal hereinafter)S5 to be superimposed on the video signal S3.

The SS anti-duplication control signal generation section 14 is providedwith an anti-duplication control signal string generation section forgenerating an anti-duplication control signal string used for spectralspread and multiplication section for multiplying the generatedanti-duplication control signal string by the PN code string PSr forspectral spread though they are not shown in the drawing.

In the case of this example, the anti-duplication control signal stringgeneration section completes an anti-duplication control signal stringin 1 horizontal interval synchronous with the generation timing of thePN code string PS, in other words, a delimiter of bit occurs, andgenerates a anti-duplication control signal string having the same bitcontent in the subsequent repetition horizontal interval. To control thetiming, the enable signal EN form the PN generation control section 16is supplied to the SS anti-duplication control signal generation section14. The anti-duplication control signal string is a low bit signalcomposed of 1 bit to several bits per 1 horzontal interval.

The SS anti-duplication control signal S5 generated in the SSanti-duplication control signal generation section 14 is supplied to theD/A conversion circuit 192. The D/A conversion circuit 192 converts theSS anti-duplication control signal S5 to an analog SS anti-duplicationcontrol signal S5A and supplied it to the addition section 19.

The addition section 19 superimposes the analog SS anti-duplicationcontrol signal S5A on the analog video signal S3 to generates an outputvideo signal S6A, and outputs it. As described herein above, theaddition section 19 functions as a superimposition means forsuperimposing the SS anti-duplication control signal S5A which is theanti-duplication control signal spectrally spread using the PN codestring PSr. In this case, the SS anti-duplication control signal S5A issuperimposed in a level lower than the dynamic range of the videosignal. The video signal is not deteriorated because of superimposing inthe manner as described herein above.

In the above-mentioned example, PN code strings PN11, PN12, PN13, . . .are generated respectively during 1 horizontal interval every secondhorizontal interval and the respective PN strings are repeated over twohorizontal interval, however, it may be the case that using the enablesignal EN having 1 horizontal interval of low level signal per threehorizontal periods, PN code strings PN11, PN12, PN13, are generated on 1horizontal interval with 2 horizontal intervals apart, and therespective PN code strings are repeated over three horizontal intervalsas shown in FIG. 4(H).

The PN code PSr is generated as described herein above, and the bitdelimiter is generated with at least the horizontal period based on thePN code string PSr, and by spectrally spreading the anti-duplicationcontrol signal having the same bit content per 1 horizontal interval inthe repeating interval of the PN code PSr, a spectrally spread signal,in which chips having the same data in the vertical direction in aplurality of horizontal intervals where the PN code is repeated isarranged and chips having the same data in the time axis of the pictureunit is arranged, is generated.

FIG. 7 shows generation structure of the PN code PSr generated by the PNrepetition section in this example, that is, the FIG. 7 is a diagram forillustrating mapping of the PN code PSr to the video signal. Asdescribed herein above, in this example, the PN code string PSr suppliedfrom the PN repetition section 18 has a period of 1 vertical interval,and a plurality of horizontal intervals contains the same PN code stringas 1 horizontal interval.

In FIG. 7, for convenience of simple description, 1 vertical interval isdivided into two divided-intervals, the PN code string PN11 is repeatedon the first half of 128 horizontal intervals, and the PN code stringPN12 is repeated on the second half of 128 horizontal intervals. In thecase of FIG. 7, exemplarily for description the PN code strings PN11 andPN12 contain 4 chips respectively. The PN code PSr is rest based on thereset signal having the vertical period, therefore all the verticalintervals are mapped in the same way.

As obvious in FIG. 7, chips having the same data are arranged in thevertical direction in a plurality of horizontal intervals where the PNcode is repeated, and chips having the same data are arranged in thetimed xis direction in the picture unit. In detail, chips havingdifferent data are generated in the horizontal direction, but chipshaving the same data are arranged repeatedly on a plurality ofhorizontal intervals where the PN code is repeated in the verticaldirection and also chips having the same data are arranged repeatedly inthe time axis direction. The anti-duplication control signal iscompleted in 1 horzontal interval for the respective same PN codestrings PN11, PN12, PN13 . . . in 1 horizontal interval unit, therefore,four planes on which the same chips are formed in the vertical directionand time axis direction in a plurality of horizontal intervals where thePN code is repeated is formed and total 8 planes are conceptually formedin this example as shown in FIG. 7 for the SS anti-duplication controlsignal.

Therefore, in the case that the spectrally spread anti-duplicationcontrol signal is superimposed on the video signal using the PN codestring PSr, if noise is removed utilizing correlation of the videosignal as described herein above, operation of taking the differencebetween adjacent horizontal lines, adjacent fields, or adjacent framesdoes not result in detection of the SS anti-duplication control signalas a difference.

Hence, in the case that the noise removal utilizing correlation of thevideo signal or interpolation or thinning in the horizontal or time axisdirection is performed as described herein above in the output device10, the device such as recording device, described hereinafter, forreceiving supply of the video signal from the output device 10, orbetween the output device 10 and a device which receives supply of thevideo signal from the output device 10, the video signal on which thespectrally spread anti-duplication control signal (SS anti-duplicationcontrol signal) is superimposed is transmitted and supplied to asubsequent device consistently.

Because the anti-duplication control signal is superimposed on the videosignal after the anti-duplication control signal was spectrally spread,the SS anti-duplication control signal does not deteriorate the videosignal, and also the SS anti-duplication control signal can not beremoved from the video signal.

Furthermore, according to this embodiment, because different PN codesare used respectively on a plurality of horizontal intervals and bit ofthe additional information can be changed for the respective PNcode, asthe whole, the increased quantity of information spectrally spread andsuperimposed as the additional information is transmitted.

FIG. 8 shows the relation between the anti-duplication control signaland video signal in the form of a spectrum. The anti-duplication controlsignal is a low bit rate signal containing small quantity ofinformation, and the narrow-band signal as shown in FIG. 8( a). Theanti-duplication control signal becomes a wide-band signal as shown inFIG. 8( b) when subjected to spectral spread. When, the spectral spreadsignal level is reduced in inverse proportion to enlargement ratio ofthe band width.

The SS anti-duplication control signal S5A namely the spectral spreadsignal is then superimposed on the video signal in the addition section19, when, the SS anti-duplication control signal S5A is superimposed atthe level lower than the dynamic range of the video signal which isserved as the information signal as shown in FIG. 8( c). Bysuperimposing in such way, the main information signal is notdeteriorated. Therefore, when the video signal on which the SSanti-duplication control signal is superimposed is supplied to a monitorreceiver to display a picture, a good played back picture is obtainedwithout adverse effect of the SS anti-duplication control signal.

On the other hand, as described hereinafter, when inversion spectralspread is performed to detect the SS anti-duplication control signal inthe recording side, the SS anti-duplication control signal is restoredto the original narrow-band signal as shown in FIG. 8( d). By giving asufficient band spread factor, the power of the inversion spreadanti-duplication control signal exceeds that of the information signal,and the information signal becomes detectable.

In this case, because the SS anti-duplication control signalsuperimposed on the analog video signal is superimposed on the same timeinterval and the same frequency, it is impossible to remove or modifythe analog video signal by simple using of a frequency filter orreplacement of an information.

Therefore, the SS anti-duplication control signal superimposed on thevideo signal will not be removed, and the SS anti-duplication controlsignal is supplied consistently to a monitor receiver or recordingdevice.

As described herein above, the analog output video signal S6A on whichthe anti-duplication control signal S5A is superimposed is supplied to amonitor receiver for displaying a picture or a recording device 20described herein under.

[Video Signal Recording Device of the First Embodiment]

Next, a recording device 20 which receives the video signal S6A from theabove-mentioned output device 10 and records the video signal therein isdescribed.

FIG. 9 is a block diagram for illustrating the video signal recordingdevice 20 (referred to simply as recording device hereinafter) used forthe video signal duplication control system of this embodiment. In otherwords, the recording device 20 is equivalent to a recording system ofthe DVD device in the first embodiment.

The recording device 20 is provided with a coding section 21, writesection 22, detection section 23 for detecting an anti-duplicationcontrol signal spectrally spread and superimposed on the video signal(referred to as SS anti-duplication control signal detection section),duplication control section 24 for performing control such asduplication permission or duplication inhibition, sync separationsection 25, PN generation control section 26, PN generation section 27,PN repetition section 28, and A/D conversion circuit 29. A recordingmedium 200 is a DVD where the recording device 20 writes the videosignal.

The video signal S6A supplied from the output device 10 is converted tothe digital video signal S21 by the A/D conversion circuit 29 andsupplied to the coding section 21, SS anti-duplication control signaldetection section 23, and sync separation section 25.

Upon receiving the digital video signal S21, the coding section 21performs coding processing such as removal of the video sync signal anddata compression of the digital video signal to generates a recordingdigital video signal S22 to be supplied to the recording medium 200, andsupplies it to the write section 22.

The sync separation section 25 extracts the horizontal sync signal H andvertical sync signal V from the uncoded digital video signal S21 andsupplies it to the PN generation control section 26.

In this embodiment, the PN generation control section 26 of therecording device 20 has the same structure as that of the PN generationcontrol section 16 of the output device 10 described using FIG. 3.Therefore, the PN generation control section 26 having the structureshown in FIG. 3 is described herein for the purpose of description.

The PN generation timing signal generation section 161 of the PNgeneration control section 26 generates a PN code rest timing signal RE(referred to simply as reset signal RE hereinafter) for providing areset timing of the inversion spread PN code string used for spectralspread corresponding to the output device 10 using the vertical syncsignal V as the reference signal, and generates an enable signal ENcorresponding to the enable signal EN in the output device 10 describedherein above. The reset signal RE generated herein is the same signal asthe PN code reset timing signal RE generated in the PN generationcontrol section 16 of the output device described herein above, andprovides timing corresponding to the starting position of a verticalinterval of the video signal.

The PN clock generation section 162 of the PN generation control section26 generates a PN clock signal PNCLK synchronous with the horizontalsync signal H. The clock signal PNCLK is a signal corresponding to theclock signal PNCLK used in the output device 10 described herein before.The timing signal generation section 163 of the PN generation controlsection 26 generates various timing signals based on the horizontal syncsignal H.

The reset signal RE, enable signal EN, and clock signal PNCLK aregenerated in the PN generation control section 26 and are supplied tothe PN generation section 27. The enable signal EN and clock signalPNCLK from the PN generation control section 26 are supplied also to thePN repetition section 28.

The PN generation section 27 has the same structure as that of the PNgeneration section 17 of the output device described herein before usingFIG. 5, and the PN repetition section 28 has the same structure as thatof the PN repetition section 18 of the output device 10 described hereinbefore in FIG. 6. Therefore, the quite same PN code string PSr as thatobtained for spectral spread in the output device 10 described hereinbefore is obtained, and the obtained PN code string PSr is supplied tothe SS anti-duplication control signal detection section 23.

In this embodiment, the SS anti-duplication control signal detectionsection 23 is provided with a PN code generator and multiplicationcircuit to have a function as a spectral inversion spread means forperforming spectral inversion spread and extracting the anti-duplicationcontrol signal superimposed on the video signal.

The SS anti-duplication control signal detection section 23 spectrallyinversion spreads the video signal of each vertical intervalsuperimposed on which the SS anti-duplication control signal issuperimposed using the inversion spread PN code string that is the samePN code string PSr as the PN code string used for spectral spread, andextracts the anti-duplication control signal superimposed on the videosignal. The extracted anti-duplication control signal S23 is supplied tothe duplication control section 25.

The duplication control section 25 decodes the anti-duplication controlsignal S23, and judges whether the video signal supplied to therecording device 20 is a signal of duplication inhibited or duplicationpermitted. Based on the judgement result, the duplication controlsection 25 generates a write control signal S24 and supplies it to thewrite section 22, and performs duplication prevention control such aswriting permission or writing inhibition of the video signal S22.

The write section 22 writes the video signal S22 in the recording medium200 if the write control signal S24 is a signal for permitting writing,and on the other hand, does not write the video signal S22 in therecording medium 200 if the write control signal S24 is a signal forinhibiting writing.

As described herein above, the recording device 20 of this embodimentspectrally inversion spreads the video signal on which the SSanti-duplication control signal is superimposed correspondingly to theoutput device 10 using the same PN code string as the PN code string PSrused for spectral spread of the anti-duplication control signal, andextracts the anti-duplication control signal superimposed on the videosignal.

In this case, as described herein before, the video signal outputtedfrom the output device 10 has the SS anti-duplication control signalsuperimposed thereon having the same data in the vertical direction on aplurality of horizontal interval on which the PN code is repeated andhaving the same data in the time axis direction.

Hence, as described herein before, even if the noise is removedutilizing correlation of the video signal, the SS anti-duplicationcontrol signal superimposed on the video signal will not be removed.Also, if thinning out or interpolation is performed in the verticaldirection or time axis direction, the SS anti-duplication control signalsuperimposed on the video signal will not be damaged.

Therefore, even if special speed playback is performed or so-called cutedition is performed when the video signal is inputted to the recordingdevice, it does not occur that the SS anti-duplication control signaldeteriorates or the control content of the anti-duplication controlsignal which the SS anti-duplication control signal indicates cannot bejudged. In other words, in the recording device 20, the spectrallyspread anti-duplication control signal superimposed on the video signalis extracted consistently and correctly and the duplication preventioncontrol corresponding to the extracted anti-duplication control signalis performed.

In the above-mentioned first embodiment, in the output device 10 andrecording device 20, the PN code string is generated at the same timingas that of vertical sync signal respectively in the output device 10 andrecording device 20 by generating the PN code reset timing signal REusing the video sync signal, in this case using the vertical syncsignal, as the reference signal.

Hence, in the recording device 20, for example, it is not required thatthe PN code string which spectrally spreads the anti-duplication controlsignal superimposed on the video signal and phase control is performedso as to generate the PN code string for inversion spread at the sametiming, therefore, the anti-duplication control signal is extractedrapidly by performing inversion spectral spread.

Further, as described herein above, in the output device 10 andrecording device 20, because the frequency of the clock signal PNCLK isdetermined using the horizontal sync signal as the reference signal,both in the output device 10 and in the recording device 20, the clocksignal having the same frequency can be generated consistently.

[Modified Examples of the Video Signal Output Device of the FirstEmbodiment]

[First Modified Embodiment]

In the above-mentioned example, the PN generation section has only onePN generator, but the PN generation section 17 may be provided with aplurality of PN generators, and the plurality of PN generators areswitched every plurality of vertical intervals, thereby additionalinformation to be superimposed can be increased.

FIG. 10 is a diagram for describing mapping of the PN code PSr on thevideo signal in this case. In the example in FIG. 10, the PN codestrings PN11, PN12 supplied from one PN generator to be reset at thevertical period repeat over a plurality of horizontal intervals in thefront plurality of vertical intervals in the time axis direction asdescribed herein before, and the additional information spectrallyspread using different two PN code strings PN11 and PN12 is superimposedin the vertical direction. In the rear plurality of vertical interval inthe time axis direction, another PN code generator is used, the PN codestrings PN21, PN22 supplied from this PN code generator repeat similarlyover a plurality of horizontal intervals, and the additional informationspectrally spread using the different two PN code strings PN21 and PN22is superimposed.

In this case, switching timing of the plurality of PN generators issynchronized with the detection timing of I-picture (Intra-codedpicture) obtained in, for example, decoding section 12. In detail, inthe case of this example, though the video signal was subjected to datacompression using MPEG system in which predictive coding was employed,the I-picture is an I-picture that is generated by coding one framevideo signal as it is without using predictive coding, in the case ofP-picture (Predictive-coded picture) or B-picture (Bidirectionally-codedpicture) generated using motion compensative prediction, the I-pictureprevents playback image quality from being deteriorated in the time axisdirection, and usually, is inserted at a certain period of a pluralityof vertical intervals.

When the I-picture is detected by the decoding section 12, the detectiontiming signal is transmitted to the PN generation control section 16.Then the PN generation control section 16 switches a plurality of PNgenerators which is components of the PN generation section 17correspondingly to the detection timing of the I-picture.

In the case of analog signal, timing information for switching the PNgenerator may be inserted in the specified horizontal interval of thevertical blanking time period every plurality of vertical intervals.

[Second Modified Example]

Though in the example described herein above, the PN generation section17 is reset using the reset signal RE having the vertical periodsynchronous with the vertical sync signal V so that the repetitioninterval of the PN code string coincides with the plurality ofhorizontal interval in one vertical interval, spectral spread of theadditional information using a plurality of PN code strings can beperformed in the time axis direction in which the repetition interval ofthe PN code string is a plurality of vertical intervals in the resetperiod. In the case of this example, the PN generation section 17 mayhave only one PN generator for performing sufficient function.

Mapping of the PN code PSr for the video signal used in the case of thesecond modified example is shown in FIG. 11. In the case of thisexample, the repeated PN code string 11 is generated in all thehorizontal intervals. In the rear plurality of vertical intervals, therepeated PN code string 12 is generated in all the horizontal intervals.

[Third Modified Example]

A time chart in the case of PN generation control in the third modifiedexample is shown in FIG. 13. In the case of this example, the PNgeneration section have one PN generator, the detection timing signal ofthe above-mentioned I-picture is a reset signal as shown in FIG. 13, andthe reset signal is a signal having one period of a plurality ofvertical intervals.

The enable signal EN is a signal generated based on the vertical syncsignal V (FIG. 13(B)) or a signal (FIG. 13(C)) of low level (active)during 1 vertical interval with two intervals apart in between.

The PN clock PNCLK supplied to the PN generator is a signal havinghorizontal period synchronous with the horizontal sync signal H as shownin FIG. 13 (D). The PN clock PNCLK may be a signal having a period of aplurality of horizontal intervals.

In the case of such structure, PN code strings P11, P12, . . . aregenerated on one vertical interval with one or a plurality of verticalintervals apart in between as shown in FIG. 13(E) from the PN repetitionsection 18, and the PN code string PSr in which the above-mentioned PNcode strings P11, P12 . . . repeat over a plurality of verticalintervals determined by the period of the enable signal is obtained.

Therefore, the structure described above results in mapping of the PNcode PSr for the video signal of the third example as shown in FIG. 12.In detail, 1 chip of the PN code is allocated to 1 horzontal interval ora plurality of horizontal intervals, and the anti-duplication controlsignal is spectrally spread as data which is completed during 1 verticalperiod per one PN code. The additional information spectrally spreadusing one PN code string repeats over a plurality of vertical intervals.

As described herein above, the additional information spectrally spreadusing a plurality of PN code strings is arranged in the time axisdirection every plurality of vertical intervals. Therefore, quantity ofinformation of the additional information can be increased in the timeaxis direction.

In the case of third modified example, because one chip having the samedata constitutes the horizontal direction, the additional informationcan be transmitted without adverse effect of thinning out in pixel unitand interpolation by changing the picture size.

[Video Signal Output Device of the Second Embodiment]

FIG. 14 is a block diagram for illustrating the second embodiment of thevideo signal output device in accordance with the present invention, andin the drawing, the same components as components of the firstembodiment described in FIG. 2 are given the same characters as used inFIG. 2, and detailed description is omitted for these components.

In the first embodiment, the same PN code is generated over a pluralityof horizontal intervals or a plurality of vertical intervals by usingrepeatedly a part of the PN code string generated from one PN codegenerator, however, in the second embodiment, a plurality of PN codegenerators are provided, spectral spread is performed similarly asdescribed herein before by switching these PN generators with PNgeneration controlling. Further in the second embodiment, someperformance, which is difficult to be realized in the first embodiment,can be realized in the second embodiment by using a plurality of PNcodes.

In the second embodiment, two PN generation sections 32 a and 32 b areprovided, and a switch circuit 33 is provided for selecting andswitching between PN code strings PNa and PNb supplied from these PNgeneration sections 32 a and 32 b.

The horizontal sync signal H and vertical sync signal V supplied fromthe sync separation section 15 are supplied to the PN generation controlsection 31. The PN generation control section 31 generates reset signalsREa and REb for the above-mentioned two PN generation sections 32 a and32 b, enable signals ENa and ENb, and clock signal PNCLK, controlsgeneration of the PN code strings PNa and PNb from the two PN generationsections 32 a and 32 b, and generates a switching control signal SW forswitching the switch circuit 33.

The switch circuit 33 supplies the PN code string obtained by switchingand selection to the SS anti-duplication control signal generationsection 14, the anti-duplication control signal S4 supplied from theanti-duplication control signal extraction section 13 is spectrallyspread in the same way as used in the above-mentioned first embodimentto generate the SS anti-duplication control signal S5. In the same wayas described hereinbefore, the signal S5 is subjected to D/A conversionby means of D/A converter 192 to convert it to an analog signal, and theaddition section 19 superimposes the analog signal on the video signalS3 and outputs it as an output signal S6A.

In the second embodiment, to perform mapping of the PN code for thevideo signal similarly as FIG. 7, a signal as shown in FIG. 15, and thetwo PN generation sections 32 a and 32 b are controlled, and the switchcircuit 33 may be switched under controlling.

In detail, the reset signals REa and REb reset the two PN generationsections 32 a and 32 b with the horizontal period as the horizontalperiod signal as shown in FIG. 15(A). The enable signals ENa and ENb arealways in enabling. The switching control signal SW is a signal which ischanging between high level and low level alternately every repeatingplurality of horizontal intervals as shown in FIG. 15(B).

Hence, the two PN generation sections 32 a and 32 b generate always PNcode strings PNa and PNb having 1 horizontal period respectively, theswitch circuit 33 extracts alternately every required plurality ofhorizontal intervals, and generates the PN code string as generated inthe first embodiment as shown in FIG. 15(C). Therefore, in the quitesame way as used in the above-mentioned first embodiment, mapping of thePN code as shown in FIG. 7 can be realized.

To perform mapping as shown in FIG. 11, two additional PN generationsections my be added.

To perform mapping as shown in FIG. 11, a signal which repeatsalternately between high level and low level every plurality of verticalintervals may be used instead of the switching control signal SW shownin FIG. 15(B).

Further, to perform mapping as shown in FIG. 12, a signal as shown inFIG. 16 is generated, two PN generation sections 32 a and 32 b arecontrolled and the switch circuit 33 may be switched under controlling.

In detail, the reset signals REa and REb reset two PN z generationsections 32 a and 32 b with the vertical period as the vertical periodsignal as shown in FIG. 16(A). The enable signals ENa and ENb are alwaysin enabling condition. The PN clock signal PNCLK is used as a clock of 1horizontal period or a plurality of horizontal periods synchronous withthe horizontal sync signal Has shown in FIG. 16(C), and the switchingcontrol signal SW is a signal which changes alternately between highlevel and low level corresponding respectively to the PN code stringsPNa PNb every repeating plurality of vertical intervals as shown in FIG.16(C).

Hence, the two PN generation sections 32 a and 32 b generates always thePN code strings PNa and PNb having 1 vertical period respectively, andthe switch circuit 33 extracts alternately the PNa and PNb everyrequired plurality of vertical intervals, and generates a PN code stringas shown in FIG. 16(D). Therefore, in the quite same way as used in theabove-mentioned first embodiment, mapping as shown in FIG. 12 isrealized.

For resetting the PN generation sections 32 a and 32 b in the case ofFIG. 16, detection timing of the above-mentioned I-picture may be used.

[Second Embodiment of the Video Signal Recording Device]

FIG. 17 is a block diagram for illustrating the second embodiment of therecording device corresponding to the second embodiment of the videosignal output device.

In the recording device 40 of this second embodiment, the samecomponents as those described in the recording device 20 of the firstembodiment shown in FIG. 9 are given the same characters as used in FIG.9 and detailed description of the components is omitted.

In this second embodiment, two PN generation sections 42 a and 42 b areprovided for inversion spread, and a switch 43 is provided for switchingand selecting between a PN code strings PNa and PNb supplied from therespective PN generation sections 42 a and 42 b.

The horizontal sync signal H and vertical sync signal V from the syncseparation section 25 are supplied to the PN generation control section41. The PN generation control section 41 generates reset signals REa andREb for the above-mentioned two PN generation sections 42 a and 42 b,enable signals ENa and ENb, and clock signal PNCLK, controls generationof the PN code strings PNa and PNb supplied from the two PN generationsections 42 a and 42 b, and generates a switching control signal SW forswitching circuit 43.

From this switch circuit 43, the same PN code string as the PN codestring used for spectral spread is obtained. The switch circuit 43supplies the PN code string to the SS anti-duplication control signaldetection section 23, and restores the anti-duplication control signalS23 superimposed on the video signal by spectral inversion spread in thesame way as used in the above-mentioned first embodiment. The restoredanti-duplication control signal S23 is supplied to the duplicationcontrol section 24 to decode, and the write control signal S24 suppliedfrom the duplication control section 24 controls the write section 22.

[Modified Example of the Second Embodiment]

In the case that the output device 30 and recording device 40 of thesecond embodiment are used, mapping of the PN code for the video signal,which can not be realized in the first embodiment, is realized.

In detail, as shown in FIG. 18(A), the PN code is generated at a rate ofone chip per 1 vertical interval or a plurality of vertical intervals inthe time axis direction, and the PN code from the PN generator for theother PN series out of the plurality of PN series is generated similarlyin the zone divided in the vertical direction. In FIG. 18(A), forexample, “1, 2, 3, 4, . . . ” is the PN code string of chip unitgenerated from the PN generator 32 a, and “5, 6, 7, 8, . . . ” is the PNcode string of chip unit generated from the PN generator 32 b.

For mapping shown in FIG. 18(A), various timing signal as shown in FIG.19 may be generated from the PN generation control section 31.

In detail, from two PN generators 32 a and 32 b, PN code strings PNa andPNb as shown in FIGS. 18(B) and 18(C) are generated successively inresponse to the clock PNCLK as shown in FIG. 19(A). The PN generationcontrol section 31 generates the switching control signal SW forcontrolling the switch circuit 33 so as to select alternately the PNcode strings PNa and PNb every ½ vertical period as shown in FIG. 19(D).Thereby, the PN code string as shown in FIG. 19(E) of mapping shown inFIG. 18(A) is obtained from the switch circuit 33.

Next, an example of mapping shown in FIG. 18(B) is obtained in the casethat the switching control signal SW shown in FIG. 19(D) is switchedevery ½ horizontal interval. Hence, two PN code strings generated in thetime axis direction is generated in a plurality of separate intervals inthe horizontal direction.

An example of mapping shown in FIG. 18(C) is obtained in the case thatthe PN generators 32 a and 32 b are reset with the vertical period, 1chip is generated per 1 horizontal period or a plurality of horizontalperiods, and the switch circuit 33 is switched every ½ horizontalinterval.

Further, an example of mapping shown in FIG. 20 is obtained in the casethat, in addition to the example of FIG. 18(C), two PN generators areadded, the total four PN generators are grouped into two two-generatorgroups, the PN generator is switched between two groups alternatelyevery plurality of vertical intervals to perform the above-mentioned PNgeneration control using two PN generators.

In the case of embodiments described herein above that a plurality of PNgenerators are used, it is possible to generate the PN code string indifferent intervals not only in the vertical direction and time axisdirection but also in the horizontal direction and it is possible toincrease additional information.

[Third Embodiment]

The third embodiment is an application example shown in FIG. 7 of thefirst embodiment. In the case that the video signal of the systemincluding MPEG system is subjected to data compression, the video signalis often divided in one picture unit into small blocks such as block orcode equivalent individually to minute rectangular areas of a picture.Alternatively, the video signal is subjected to DCT (Discrete cosinetransformation).

In the case of DCT, when a spectrally spread additional information issuperimposed on an analog video signal or digital video signal, it canhappen for a high frequency signal that the additional information ismissed as data or deteriorated.

The third embodiment is presented in view of this problem. In detail, inthe third embodiment, the PN code string is mapped so that 1 chip of thespectral spread signal is allocated on each 1 block which is the unit tobe subjected to DCT before DCT is applied. A block having one block ormore, for example, a macro-block having four blocks may corresponds to 1chip. In such case, the spectral spread signal is contained in the DCcomponent (direct current component) when the spectral spread signal issubjected to DCT, and the spectral spread signal will not be missed ordeteriorated.

For example as shown in FIG. 21, a video signal is divided into blocksBK having 8 pixels×8 pixels, the blocks BK are subjected to DCTprocessing in a block BK unit. Herein for example, the clock of 8 pixelunit contained in the horizontal direction of each block BK is used asthe PN clock signal PNCLK, and the PN code string of 1 horizontalinterval generated in the horizontal direction as described herein aboverepeats over 8 horizontal intervals in the vertical direction of theblock BK as described in the first embodiment. Hence, the information ofthe same chip is contained in 1 block BK, and thus it is prevented thatthe PN code string is missed as data or deteriorated.

FIG. 22 is a block diagram for illustrating a superimposition circuitsection for additional information in the third embodiment.

An analog video signal inputted through the input terminal 1001 issupplied to an addition circuit 1002 and also supplied to the syncseparation circuit 1010. The horizontal sync signal and vertical syncsignal outputted from the sync separation circuit 1010 are supplied to atiming signal generation section 1008 and also supplied to a PNgeneration control section 1012 which corresponds to the PN generationcontrol section 16 in FIG. 2.

On the other hand, the timing signal for dividing into blocks outputtedfrom the timing signal generation section 1008 is supplied to the PNgeneration control section 1012. The PN generation control section 1012generates the clock signal PNCLK of every 8 pixels that is the size of ablock BK in the horizontal direction, enable signal EN which is in lowlevel during the first horizontal interval output 8 horizontal intervalsthat is the size of a block BK, and reset signal RE of the verticalperiod, and these signals are supplied to an SS anti-duplication controlsignal generation section 1011. Of course, the clock signal PNCLK andenable signal EN are synchronous with the block timing signal.

The SS anti-duplication control signal generation circuit 1011 isprovided with components of the PN generation section 17, PN repetitionsection 18, and anti-duplication control signal generation section 14 inthe example shown in FIG. 2, generates the PN code string which repeats8 horizontal intervals in the vertical direction of a block BK, andspectrally spreads the anti-duplication control signal supplied to itusing the above-mentioned PN code string to generates an SSanti-duplication control signal. The SS anti-duplication control signalgeneration circuit 1011 then supplies the generated SS anti-duplicationcontrol signal to the addition circuit 1002. In this case, as describedusing FIG. 8 hereinbefore, the SS anti-duplication control signal havinga level lower than that of dynamic range of the video signal is suppliedto the addition circuit 1002.

The addition circuit 1002 superimposes the abovementioned SSanti-duplication control signal on the video signal. The video signal onwhich the SS anti-duplication control signal is superimposed isconverted to a digital signal by the A/D converter 1003, and supplied tothe DCT processing section 1004. The DCT processing section 1004 dividesthe video signal using the timing signal supplied from the timing signalgeneration section 1008, and performs DCT operation processing.

The operation processing result from the DCT processing section 1004 issupplied to a quantization section 1005 and quantized. An output fromthe quantization section 1005 is supplied to the DCT processing section1004 through a motion compensative circuit 1006, and the motioncomponent is subjected to DCT operation. The output from thequantization section 1005 is converted to a variable length code using aHuffman code by a variable length coding section 1007, and outputted,for example, for recording or transmission.

Because the SS anti-duplication control signal is contained in thedirect current component during inversion DCT operation when thecompressed data transmitted or recorded as described herein above isdecoded, the SS anti-duplication control signal is superimposed on theanalog video signal without deterioration and restored. Therefore, theSS anti-duplication control signal is transmitted consistently and theduplication control is performed consistently.

In the example shown in FIG. 22, the case that the anti-duplicationcontrol signal is superimposed on the analog video signal is described,however, the anti-duplication control signal may be superimposed on adigital video signal after being subjected to A/D conversion.

[Other Modified Example]

In the above-mentioned embodiments, in the output devices 10 and 30,recording devices 20 and 40, the SS anti-duplication control signal issuperimposed on all the intervals of the video signal, however, the SSanti-duplication control signal may be superimposed on only theeffective picture interval excepting vertical blanking period andhorizontal blanking period. Further, the SS anti-duplication controlsignal may be superimposed not all the effective picture area. The areaon which the SS anti-duplication control signal is to be superimposedmay be prescribed desirably based on the horizontal sync signal, forexample, an area having the first several clocks of no superimpositionand following several ten clocks of superimposition.

In the above-mentioned embodiments, the case of analog connection thatthe analog video signal is supplied from the output devices 10 and 30 tothe recording devices 20 and 40 is described, however, the presentinvention is applicable to digital connection.

In other words, the spectrally spread anti-duplication control signalcan be superimposed on the analog video signal and also on the digitalvideo signal.

In the recording devices 20 and 40, the processing, in which the videosignal to be supplied to the SS anti-duplication control signaldetection section is subjected previously to filtration to extractpartially the video signal of low level on which the spectrally spreadanti-duplication control signal is superimposed, and the extracted suchvideo signal is supplied to the SS anti-duplication control signaldetection section, may be used.

In the above-mentioned embodiments, the output device and recordingdevice which are DVD devices are described, however, the presentinvention is by no means limited to the case, the present invention maybe applied to output devices and recording devices having VTR, digitalVTR, video disk, and video CD.

In the above-mentioned embodiments, the processing, in which theanti-duplication control signal added on the video signal recorded in arecording medium 100 is extracted, spectrally spread using the PN code,and superimposed on the video signal to be supplied to the recordingdevices 20 and 40, is described, however, a recording medium in whichthe video signal having the spectrally spread anti-duplication controlsignal superimposed previously thereon may be used.

In detail, the additional information is spectrally spread using thespread code having 1 period of the interval in 1 horizontal interval,having 1 period of the interval of shorter than 1 vertical interval, orhaving 1 period of the interval in a plurality of vertical intervalswith reference to the video sync signal with respect to the video signalto be recorded in a recording medium, and the spectrally spreadadditional information is superimposed on the video signal. In thiscase, the spectrally spread additional information is superimposed onthe video signal so that the chip having different data is arrangedevery prescribed plurality of pixels, every prescribed plurality ofhorizontal intervals, or every prescribed plurality of verticalintervals.

As described herein above, in the case of the recording medium in whichthe video signal having the spectrally spread anti-duplication controlsignal superimposed previously thereon is recorded, it is not necessaryfor the output device to perform processing such as extraction of theanti-duplication control signal, generation of the PN code, spectralspread, superimposition of the spectrally spread anti-duplicationcontrol signal on the video signal. In other words, in this case, theoutput device side only may play back and output the video signalrecorded in the recording medium.

In this case, in the recording side, similarly to the recording device20 of the above-mentioned embodiment, the PN code string for inversionspread having the same pattern as the PN code string which spectrallyspread the SS anti-duplication control signal superimposed on the videosignal is generated at the same timing as that for spectral spread withrespect to the video signal, and spectral inversion spread is performedusing this PN code string, thereby the anti-duplication control signalsuperimposed on the video signal is extracted.

In the case that the spectrally spread anti-duplication control signalis superimposed on the video signal recorded in the recording medium, aslong as the recording device side has a function to spectrally spreadand extract the anti-duplication control signal, the anti-duplicationcontrol signal superimposed previously on the video signal is extractedand thus the duplication control is performed effectively.

The method, in which the output device is provided with a generationsection for generating the anti-duplication control signal and theanti-duplication control signal generated in the output device isspectrally spread using the PN code string and then superimposed on thevideo signal, may be used.

In this case, if the anti-duplication control signal is not recordedoriginally in a recording medium or if the spectrally spreadanti-duplication control signal is not superimposed, theanti-duplication control signal is generated in the output device, andthe duplication control is performed in the recording device side usingthe anti-duplication control signal to be superimposed on the videosignal.

In the above-mentioned embodiments, the case that the output device andrecording device of DVD devices are used as a duplication preventioncontrol device is described, however, the present invention is by nomeans limited to the case. For example, the present invention can beapplied to the case that the invention is applied to an output device ofa broadcast station side for outputting television signals, andtelevision signals to be transmitted on which the spectrally spreadanti-duplication control signal is superimposed is transmitted. In thereception side, the television signal is subjected to inversion spectralspread to extract the anti-duplication control signal superimposed onthe video signal, and the duplication prevention control of the videosignal is performed based on this anti-duplication control signal.

Of course, the present invention can be applied to the output device andreception device of the video signal in the case that the video signalis transmitted/received through a cable such as cable television.

In the above-mentioned embodiment, the anti-duplication control signalis superimposed as an additional information, however, the additionalinformation to be superimposed on the video signal is not limited to ananti-duplication control signal.

For example, a copyright information which allows us to identify thecopyright holder of the picture to be played back from the video signalmay be superimposed on the video signal. In this case, because thecopyright holder is recognized by performing inversion spectral spreadof the copyright information superimposed on the video signal and byextracting the copyright information, this method is useful forprevention of piracy, and the piracy is noticed easily in the case thatthe picture the copyright of which is held by the copyright holder isused without previous consent.

As described herein above, the copyright information can not removed ordeteriorated even if the anti-duplication control signal is subjected tonoise removal utilizing the correlation of the video signal, thinningout or interpolation of pixels in the horizontal direction formed by thevideo signal, or thinning out or interpolation between fields in thetime axis direction, and thus the anti-duplication control signal isextracted and used consistently.

EFFECT

As described hereinbefore, according to the video signal transmissionmethod, superimposed information extraction method, video signal outputdevice, video signal reception device, video signal recording medium inaccordance with the present invention, the additional information havingthe same data in the horizontal direction and time axis direction issuperimposed repeatedly. Thereby, the spectrally spread additionalinformation superimposed on the video signal will not be removed ordeteriorated even if the additional information is subjected to noiseremoval utilizing correlation of the video signal.

The spectrally spread additional information superimposed on the videosignal will not be changed even if the video signal is changed when thevideo signal is subjected to thinning out or interpolation in thehorizontal direction or thinning out or interpolation in the time axisdirection.

Hence, the spectrally spread additional information superimposed on thevideo signal is transmitted consistently, and in the reception side, thespectrally spread additional information superimposed on the receivedvideo signal is detected consistently.

Further, according to the present invention, because a plurality ofdifferent PN code strings is generated respectively in the horizontaldirection, vertical direction, or time axis direction and different dataare superimposed as the additional information, thus the quantity ofadditional information to be superimposed can be increased.

1. A method for superimposing additional information on a video signalthat includes a plurality of picture units in a time axis direction,wherein each of said picture units is formed by arranging a plurality ofhorizontal direction units in a vertical direction, said methodcomprising the steps of: generating least one code string composed of aplurality of chips; superimposing said additional information on saidvideo signal using said code string by allocating a same chip of saidcode string on a plurality of horizontal direction units of a pictureunit or on a plurality of the picture units; arranging chips having thesame data in the vertical direction in a plurality of horizontalintervals where the code is repeated; and arranging chips having thesame data in a time axis direction in each picture unit, so that thepicture unit is completed in one horizontal interval for the samerespective code strings and two code strings are supplied in twohorizontal front strips of the picture unit.
 2. The method as claimed inclaim 1, wherein said step of superimposing superimposes said additionalinformation on said video signal using said code string by allocatingthe same chip of said code string on the plurality of horizontaldirection units of the picture unit and on the plurality of pictureunits.
 3. The method as claimed in claim 1, wherein said step ofsuperimposing superimposes said additional information on said videosignal using said code string by repeatedly allocating the same chip ofsaid code string along the vertical direction or a time axis direction.4. The method as claimed claim 1, wherein said step of superimposingsuperimposes said additional information on said video signal using saidcode string by repeatedly allocating the same chip of said code stringalong both the vertical direction and a time axis direction.
 5. Themethod as claimed in claim 1, further comprising the steps of: arrangingfirst and second code strings to be reset at a vertical interval torepeat over a plurality of horizontal intervals in a front plurality ofvertical intervals in a time axis direction, so that the first andsecond code strings are superimposed in the vertical direction; andarranging two different codes in a rear plurality of vertical intervalsin the time axis direction, so that the first and second code stringsare also superimposed in the vertical direction; and arranging twodifferent codes in a rear plurality of vertical intervals in the timeaxis direction, so that the first and second code strings are alsosuperimposed on the picture unit.
 6. The method as claimed in claim 1,further comprising the steps of: arranging a first code string in allhorizontal intervals in a front plurality of vertical intervals of eachpicture unit; and arranging a second code string in all horizontalintervals in a rear plurality of vertical intervals of each pictureunit.
 7. The method as claimed in claim 1, further comprising the stepsof: allocating one chip of the code string to a plurality of horizontalintervals, so that data of the code string is completed during onevertical period per picture unit; and repeating the code string over aplurality of horizontal intervals.
 8. The method as claimed claim 1,further comprising the step of: arranging the code string at a rate ofone chip per vertical interval in a time axis direction, so that data ofthe code string is complete during one horizontal period per pictureunit.
 9. The method as claimed in claim 1, further comprising the stepsof: arranging two code strings in a time axis direction; and switchingthe codes every one-half vertical interval, so that the two code stringsarranged in the time axis direction are arranged in a plurality ofseparate intervals in the horizontal direction.
 10. The method asclaimed in claim 3, further comprising the step of: generating two codestrings in each vertical period, with one code string being generatedper each horizontal interval.
 11. The method as claimed in claim 1,further comprising the step of: providing four code strings grouped intotwo two-code groups that are switched alternately every plurality ofvertical intervals.